Technical Guide

Variable Geometry Turbocharging

  • Dirt In Oil

    A more effective, though complex, method of turbocharging uses a turbine stage where the swallowing capacity is automatically varied while the engine is running. Turbine flow can be set to provide sufficient energy to drive compressor at the desired boost level wherever the engine RPM range is operating.

    The advantage of this system over waste gate is that all the exhaust flow is put through the turbine wheel giving increased net turbine power output.

    The Holset variable geometry system works by controlling the width of a nozzle guiding the gas flow into the turbine wheel.

  • Garett GT Ball Bearing

    • True Ball-Bearing Turbochargers

      Thanks to our single-cartridge, dual ball-bearing technology, Garrett turbochargers generate far less frictional drag and are 10 times more durable than traditional journal-bearing turbochargers. While first developed for racing, over 100,000 ball-bearing turbo have been produced for OE applications, and are now available in a range of sizes for the street.

    • Improved efficiency

      New efficient turbine stages deliver more power to your engine and allow Garrett turbochargers to spool up faster than ever. Our engineers have eliminated old efficiency killers, including on-center turbine housings, clipped turbine wheels and antiquated aerodynamics with the new GT product line.

Garrett AVNTT

Honeywell’s Garrett Advanced Variable Nozzle Turbo (AVNT) functions as a variable geometry turbocharger. It features a holistic design that minimizes the number of additional parts. The unique vane designs of the AVNT provide benchmark efficiency throughout the flow range of the unit. The vanes significantly increase turbine efficiency when compared to conventional vane designs, thereby improving engine performance with peak torque at idle.


Garrett chooses electro-hydraulic for the commercial vehicle AVNT turbochargers. The electro-hydraulic actuation utilizes the bearing system oil feed as the hydraulic source, integrates the two systems into one housing and achieves true vane position control. The AVNT is controlled by the engine management electronics by means of variable current of PWM signal.

Turbo Repair Services

We also offer Turbo Charger Parts and Repair Services.